An AIE and FRET-based BODIPY sensor with large Stoke shift: Novel pH probe exhibiting application in CO32- detection and living cell imaging

This work focused on design, synthesis and application of an AIE and FRET-based BODIPY pH sensor bearing large Stoke shift. The cyano-diphenylethylene-conjugated BODIPY derivative 4 was prepared by condensating 4-hydroxybenzene acetonitrile with 4-(diethoxymethyl)benzaldehyde and then following the typical procedure of synthesizing BODIPY derivative. Compound 4 exhibited strong fluorescence in all kinds of THE/H2O solutions due to the AIE and FRET effect. The Stoke shift of compound 4 was as large as 138 run based on the excitation of cyano-diphenylethylene moiety and the emission of BODIPY moiety. Compound 4 showed good fluorescent response to the change of pH with the pKa value at 9.79. The mechanism of compound 4 as pH probe was confirmed by H-1 NMR spectra and theoretical calculation. Compound 4 was successfully used to CO32- detection among 13 kinds of common anions both in solution and by tested strips. The experiments of living cell imaging suggested that compound 4 possessed superior bioimaging performance and presented sensitive change to pH values between 9 and 10 in living cells.